Folding expansion trailer

A folding expansion trailer, comprising

• a front frame and a rear frame, wherein the front frame and rear frame are respectively provided with two upright rods distributed at intervals, one at left and another one at right, four upright rods are distributed in a rectangle and each upright rod is equipped with a sliding sleeve that can be slid up and down;
• the upright rods on the front frame are front upright rods, while the upright rods on the rear frame are rear upright rods;
• side folding components, and each side folding component is connected between the front upright rod and rear upright rod at same side;
• each side folding component comprises a plurality of X-shaped cross articulation pieces which are sequentially articulated in a front-to-back direction, wherein one of the upper and lower ends of the first and last X-shaped cross articulation pieces is hingedly connected to an adjacent upright rod, and another end is hingedly connected to a sliding sleeve on the upright rod herein;
• a bottom support component, and the bottom support component comprises a front bottom frame, a rear bottom frame and a limiting piece;
• the front bottom frame is hinged to a bottom of the front frame and the rear bottom frame is hinged to a bottom of the rear frame, the front bottom frame is hinged with the rear bottom frame, and the limiting piece is used for supporting and limiting the front bottom frame and the rear bottom frame when the front bottom frame and the rear bottom frame are unfolded downward;
• an expansion component, and the expansion component comprises an expansion frame and connecting rod mechanisms, the expansion frame is an open ring-shaped frame with an opening forward, left and right ends of the expansion frame are hingedly connected to two rear upright rods respectively, the connecting rod mechanism is connected to the expansion frame and the sliding sleeve on the rear upright rod respectively, the connecting rod mechanisms are used to synchronously push and pull the expansion frame to unfold upwardly or to fold downwardly when the sliding sleeve on the rear upright rod slides upwardly or downwardly.